The invention relates generally to jet propulsion units, and, more particularly, to jet propulsion units which form part of an outboard motor. Still more particularly, the invention relates to draining water from the water passage or tunnel of the jet propulsion unit for the purpose of cooling the marine engine driving the impeller in the jet propulsion unit. In addition, the invention relates to filtering such water to be used for cooling the marine engine so as to remove debris from the cooling water.
Outboard motors including jet propulsion units are not new. Such prior jet propulsion units also included water passages or tunnels including water outlet ports for draining water from the water passage, as well as a conduit connecting the port to the marine engine for conducting water from the port to the cooling jacket of the marine engine. Such conduits have included "in line" water strainers (which were located downstream of the port) for the purpose of straining or filtering the cooling water to prevent passage of undesirable debris into the water jacket of the marine engine. Such "in-line" strainers undesirably and frequently required cleaning to insure continued water flow therethrough. In these past installations, water was sucked through the filter or strainer by a remote pump. This vacuum or sucking action is not self-cleaning at very low speeds or at idle, and, in fact, these systems can be self-clogging. Plastic bags, seaweed, leaves, and such can adhere to the previous "in-line" screens, thereby reducing or preventing water supply to the engine cooling jacket.
Attention is directed to the following U.S. patents:
U.S. Pat. No. 2,466,525, Wilson, issued Apr. 5, 1949 PA1 U.S. Pat. No. 3,233,573, Hamilton, issued Feb. 8, 1966 PA1 U.S. Pat. No. 3,249,083, Irgens, issued May 3, 1966 PA1 U.S. Pat. No. 4,258,642, Burmeister, issued Mar. 31, 1981 PA1 U.S. Pat. No. 4,423,696, Aker, issued Jan. 3, 1984 PA1 U.S. Pat. No. 4,437,841, Stallman, issued Mar. 20, 1984 PA1 U.S. Pat. No. 4,787,328, Inoue, issued Nov. 29, 1988 PA1 U.S. Pat. No. 4,636,175, Frazzell et al., issued Jan. 13, 1987 PA1 U.S. Pat. No. 4,699,597, Oja, issued Oct. 13, 1987 PA1 U.S. Pat. No. 4,752,257, Karls et al. issued Jun. 21, 1988 PA1 U.S. Pat. No. 4,767,366, Lang, issued Aug. 30, 1988 PA1 U.S. Pat. No. 4,832,639, Karls et al., issued May 23, 1989 PA1 U.S. Pat. No. 4,832,640, Karls, issued May 23, 1989 PA1 U.S. Pat. No. 4,861,293, McGowan et al., issued Aug. 29, 1989 PA1 U.S. Pat. No. 4,954,109, McMorries, IV, issued Sep. 4, 1990 PA1 U.S. Pat. No. 5,096,446, Tazaki et al., issued Mar. 17, 1992 PA1 U.S. Pat. No. 5,098,322, Higby, issued Mar. 24, 1992 PA1 U.S. Pat. No. 5,215,487, Gruber, issued Jun. 1, 1993 PA1 U.S. Pat. No. 5,366,397, Suganuma et al., issued Nov. 22, 1994 PA1 Canadian Patent No. 664,183, Johnson et al.
Attention is also directed to the following foreign patent: